350 MAG MPI swap to 383 Stroker Help
 

Hello all! New registered member to the forum. I own a 2003 Rinker 270 Fiesta Vee with a single 350 MAG MPI with Bravo III drive. We had issues with the boat so the past few years the boat has sat. At idle now the boat runs rough. Probably not a huge issue but enough to warrant a look into finally getting rid of the "dovish" 350. We previously had issues planing with 6 people on board and WOT never exceeded 31 MPH. Our goal is to be able to have 8 or 9 people onboard or around 1300 lbs and plane without issue and increase our WOT to around 40 MPH. Can this be done with a short block? Can we have our current motor modified to accomplish this? Is the best option a new Mercruiser 383 stroker? I am on LI, and could really use some advice and guidance because our other option is selling the boat as is and buying a new Cruisers 258 bowlder we've been eying. ;) but would love to have our Rinker if we can get some rocking performance out of it.

Thanks!

Unless you REALLY love that boat, I wouldn't spend the money required to achieve the performance you're expecting.

If you insist on modifying your boat to do what you are looking for consider this:http://www.michiganmotorz.com/stroke...mpi-p-502.html

As you can see you will spend $10K plus labor to swap to this power. You need TORQUE to achieve the results your looking for. You could possibly cdopletely rework what you have but you will only save about 25% at the end of the day.

It comes down to choices and dollars. Sounds like you need a bigger boat with twin engines.

Thank you for your response Sprink. We are prepared to drop $12k or so into a re-power just as long as the performance is a drastic improvement. At the end of the day it's still a Rinker and still a single screw, but we've owned the boat since 2008 and have taken very good care of it and spent good money making the boat right. The question is whether the 383 stroker will do the trick so we will be happy with it for the next 5 or so years before upgrading to a larger twin screw boat.

Big block. Find a take out 496 MAG HO or a 502 MAG MPI.

I was thinking about a big block but would the performance be enough considering the addition engine weight?

Yes...if you find a fresh late model 502 MPI Mag that would be the way to go. Depending on the hours on your Bravo III you might consider re-working it at the same time to handle the additional torque.

Humm, very interesting. Now would the 502 be a drop in using the current motor mounts where my 350 sits or would that need to be customized? I wonder what type of labor costs would be involved in this installation??.....

Yes the bbc sits on the same mount locations as the old school small block. You need about 3 inches in front, 2 inches either side, and 3 inches on top for engine to fit where small block is now. Stock exhausts go to the same thru-prop y-pipe.

Thats good news. I found a shop in upstate NY that specializes in rebuilt marine engines. I just spoke with them. They suggested a rebuilt 454 that is built on the 502 platform. He said they make around 510 ft lbs of torque and 430 HP and would be a drastic improvement over what I currently have. He also said my Bravo III would work just fine with this new motor. He has it in a carb ($6500) or MPI ($8000) option. Of course I would need it installed which from what I am seeing would cost around $1200-$1500 plus the shipping of the engine. Then hopefully I can sell my 350 MAG MPI for a couple grand to help my upfront costs a bit.

Thoughts?

Trying to upload a pic of what he has

http://http://www.ebay.com/itm/502-mpi-8-2-Mercruiser-replacement-motor-efi-computer-454-gen-6-dyno-tested-/262195758040